Another thing to look out for is security. Some databases may require CLR be turned on, some may not. Some servers may have cmdshell turned on, some may not.

I have a "food court" server with 40+ databases, from different vendors. As long as they don't require the above, and it is just a simple database, then it can go there. They usually have a virtual app or web server, and I just give them Management Studio and let their Windows VPN login have extra permissions on their specific database, that way they can go in and look and tweak the data if necessary. I don't give DB_Owner rights, they can back up databases. I've had vendors do unauthorized backups before. Took those rights away.

Also, any specific CLR assemblies to move, special jobs that have to run, linked servers, data loads, Reporting Services requirements, Reports, etc. (and any associated security, usernames, etc.)

These things have to be discovered, mapped, and analyzed to make sure nothing affects the others.

Again, just some things to think about.